• 한국식품영양학회지
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• 제10권2호
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• pp.228-233
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• 1997

The effects of spray drying and extrusion drying on functional properties of agar were investigated to increase the availability of agar in food industry. In case of unmodified and spray-dried agar, gel strength and viscosity were 1,070g/$ extrm{cm}^2$ and 170.50pcs, 820g/$\textrm{cm}^2$ and 17.07cps, respectively, while 523.28g/$\textrm{cm}^2$ and 12.81 in extrusion-dried product. The lowest dissolving onset and conclusion temperature were revealed in extrusion sample, where it was attained in 80 and 11$0^{\circ}C$ of unmodified, 60 and 9$0^{\circ}C$ of spray-dried, and 35 and 8$0^{\circ}C$ of extrusion-dried agar, respectively. Melting and setting in unmodified sample were showed to 110.17 and 40.52, 90.05 and 39.54$^{\circ}C$ in spray dried, and 80.01 and 36.05$^{\circ}C$ in extrusion-dried agar, respectively.

• 소성∙가공
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• 제4권4호
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• pp.390-397
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• 1995

A simple kinematically admissible velocity field is proposed to determine the final-stage extrusion load and the average extruded length in the square-die forward extrusion of non-axisymmetric bars from circular billets. The proposed velocity field is applied to the square-die extrusion of trochoidal gear-shaped bars and rectangular-shaped bars. The profile function of a rectangle is approximated by using a Fourier series. Experiments have been carried out with hard solder billets at room temperature. The theoretical predictions of the extrusion load are in good agreements with the experimental results and there is generally reasonable agreements in average extruded length between theory and experiment.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 추계학술대회논문집
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• pp.14-19
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• 1996

This study presents development of finite element simulation program and analysis of hot extrusion through square dies with mandrel. The design of extrusion dies is still an art rather than science. Die design for a new extrusion is developed from through in-plant trials. In the present paper, three-dimensional steady-state finite element simulation program is developed. The developed system is effectively used to simulate extrusion of clamp shaped hollow section. The objective of the present paper is to study the possibility of integrating this method into the design of dies for extrusion of complex section. To obtain sound product, the distributions and effects of temperature, effective strain rate, mean strain rate and mean stress are studied.

• Food Science and Biotechnology
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• 제14권6호
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• pp.758-765
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• 2005

Instant powders that only require mixing with water prior to consumption can be produced by extrusion for use in products such as instant beverages. Both extrusion processing conditions and particle size of powder are important to end-product characteristics. In this study, a twin-screw extruder was used under various processing conditions (feed moisture, barrel temperature, and screw speed) to produce extrudates from soft wheat flour, which were ground to powders with particle size ranges of less than 93, 93-145, and $145-249\;{\mu}m$. Effects of adding soy lecithin to wheat flour before extrusion were also investigated. Water absorption, solubility, suspension viscosity, and dispersibility of wheat powders were related to specific. mechanical energy measured during extrusion. Powder particle size was important to instant properties, especially ease of dispersal in water and stability to sedimentation. Addition of lecithin significantly improved dispersibility of powders.

• 소성∙가공
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• 제8권5호
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• pp.482-490
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• 1999

7000 series Al alloy with good mechanical properties has been focused with tendency to reduce the components weight of aircraft and automobile. However, it is difficult to manufacture a sound extruded product because of segregation, grain growth, casting defect, surface defect, decreasing extrudability and so on. The objective of this study is to manufacture a new 7000 al alloy more than the extrudability of A7N01 and A7003 through controlling the weight (%) Mg, Zn, Si. Hot extrusion experiments on the axisymmetric rod are performed in 500℃ and also performed analysis of the same process using unmerical analysis method, a coupled rigid-thermoviscoplastic finite element method. Extrusion limit diagram was obtained for the developed alloy by FE-simulation in order to define the relationship of extrusion speed and initial billet temperature.

• 한국공작기계학회논문집
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• 제17권4호
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• pp.1-7
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• 2008

Fine grained superplastic Zn-22%Al alloy was extruded using a laser machined micro-die to produce a micro-gear shaft. Extrusion process was conducted under a constant pressure at constant temperatures ranging from 503 to 563K. Laser machining was capable to machine a micro-die with close tolerances and adequate surface quality. The extrusion rate increased with extrusion load under constant extrusion temperature. The rate reached a steady state and became constant after a certain period. There was a small instantaneous stroke on application of the load and then a very brief primary stage which preceded steady-state flow. The micro-extrusion process was proven to produce a micro-gear shaft successfully using a fine grained superplastic Zn-22%Al alloy.

• 한국정밀공학회지
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• 제10권2호
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• pp.30-39
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• 1993

The study is concerned with the thermo-viscoplastic finite element analysis of nonisothermal hot container extrusion through conical dies. The problem is treated as a non-steady state incorporating the nonisothermal heat transfer analysis. The analysis of temperature distribution includes heat transfer though the boundary surface including conduction, convection and radiation. The analysis of heat transfer is decoupled with the analysis of deformation and the material interaction is considered through iteration procedure. The effect of important process parameters including die angle and extrusion ratio in the process is investigated. Due to the geometric feature for the container extrusion through conical dies, automatic remeshing is mandatory. Automatic remeshing is achieved by introducing the modular remeshing technique.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.214-219
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• 1998

Analytic and experimental methods have been used for the characterization of flow behavior of semi-solid Al2024 alloy. Backward extrusion experimnet was chosen to avoid the crack on the unconstrained surface. The material constants for the flow stress by the upper bound technique that agreed with experimental results were determined. The various material constants obtained for al temperature range above the solidus temperature have been fitted and represented in the function of temperature and solid fraction. The obtained result has good agreement only in the high solid fraction.

• 소성∙가공
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• 제13권7호
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• pp.623-628
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• 2004

This paper is concerned with pressure welding, which has been known as a main bonding mechanism during the cold and warm forming such as clad extrusion or bundle extrusion/drawing. Bonding characteristics between the Cu and Al plates by pressure welding are investigated focusing on the weak bonding. Experiments are performed at the cold and warm temperatures ranging from the room temperature to $200^{\circ}C$. The important factors examined in this work are the welding pressure, pressure holding time, surface roughness, and temperature. A bonding map, which can identify the bonding criterion with a weak bonding strength of IMPa , is proposed in terms of welding pressure and surface roughness fur the cold and warm temperature ranges.

• 소성∙가공
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• 제33권1호
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• pp.50-54
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• 2024

In this paper, the process of extruding Cu-10Fe alloy using a finite element analysis (FEA) was theoretically analyzed. To achieve this, the dependence of strain rate and temperature of the alloy required for the extrusion process was secured by utilizing databases for Cu and Fe and the KHL model. For microstructure analysis, FE-SEM with EDS was used to distinguish the phases present in Cu-10Fe alloy. The mechanical characteristics of Cu-10Fe alloy were secured using the results of fitting the mechanical properties of Copper and Steel from the Deform database to the KHL model. The deformation behavior within the alloy during hot extrusion was analyzed, providing insights into effective stress, effective strain, effective strain rate, and temperature. It was observed that the strain distribution was non-uniform. These research findings contribute to an improved understanding of the hot extrusion process of Cu-10Fe alloy and can aid in predicting the mechanical properties of the material.